Methods and devices providing transmyocardial blood flow to the arterial vascular system of the heart

ABSTRACT

This invention relates to methods and devices providing transmyocardial blood flow or coronary revascularization for the treatment of coronary atherosclerosis and resulting myocardial ischemia by increasing the flow of blood from one or more oxygenated blood sources within the patient to one or more sites selected in the arterial vascular system of the heart using a channel for maintaining and regulating blood flow therebetween. A valved conduit or a self-maintained channel is created between the left ventricle reservoir of oxygenated blood and the coronary artery distal to an area of obstruction by surgical and percutaneous methods. Preferably, the conduit or self-maintained channel integrally regulates the flow of blood between the oxygenated blood source and the site selected in the arterial vascular system of the heart wherein an increase in blood flow is desired.

FIELD OF THE INVENTION

[0001] This invention relates to methods and devices providingtransmyocardial blood flow or coronary revascularization for thetreatment of coronary atherosclerosis and resulting myocardial ischemia.The invention increases the flow of blood from one or more oxygenatedblood sources within the patient to one or more sites selected in thearterial vascular system of the heart using a channel for maintainingand regulating blood flow therebetween. More particularly, a valve isinserted into a channel created and maintained between, or a valvedconduit is inserted between, the left ventricle reservoir of oxygenatedblood and the coronary artery distal to an area of obstruction.

BACKGROUND OF THE INVENTION

[0002] Heart disease is a major medical ailment wherein arteries becomenarrowed or blocked with a build-up of atherosclerotic plaque or clotwhich reduces flow to tissues downstream or “distal” to the blockage.When this flow reduction becomes significant, a patient's quality oflife may be significantly reduced. In fact, heart disease patients oftendie when coronary arteries become significantly blocked.

[0003] However, technology has been developed to treat patients withcoronary artery disease. Besides drug treatment, the two most commonoperative procedures used to treat symptomatic patients are: coronaryartery bypass graft (CABG) surgery and percutaneous transluminalcoronary angioplasty (PTCA).

[0004] Conventional CABG surgery affixes a bypass graft between a portor aperture in a coronary artery wall distal to the blockage and apressurized arterial blood supply, such as the aorta, to provide aconduit for blood flow into the coronary artery to the ischemic areas ofthe heart. CABG surgery is generally initiated by directly exposing theheart to the surgeon by opening the patient's chest using knownsternotomy and retraction techniques that cut the sternum and spread therib cage open. Once the heart is exposed, the patient is connected to acardiopulmonary bypass (“CPB”) machine so that the blood supplycircumvents the heart. In this way, the heart is depressurized so thatapertures can be cut into the walls of the vessels for surgical graftattachment. The right atrium (or vena cava) and the aorta each isintubated with cannulas which are connected to an artificial pump andoxygenator. Once these major vessels are cannulated, the aorta is thenclamped proximally of the aortic bypass cannula, thereby isolating theaortic root and heart from the blood that is being circulated by theCPB. Cardioplegia is then delivered to stop the beating motion of theheart.

[0005] In one type of CABG method, the bypass grafting is achievedbetween the aorta and one of the three major coronary arteries or theirsub-branches, the left anterior descending artery (LAD), the circumflexartery (CIRC), or the right coronary artery (RCA). In such a case, asaphenous vein is usually taken from the patient's leg and istransplanted as a “homograft” to connect these vessels in order toprovide blood flow to the compromised area of the coronary circulation.Artificial grafts have also been disclosed as providing potentialutility for this purpose. An alternative CABG method uses the internalmammary artery (IMA) alone or in conjunction with the saphenous veingraft. The IMA is severed at a chosen location and is then connected toan aperture, in a coronary artery. The fluid connections between a graftand a vessel are commonly referred to as “anastomoses.” Once theanastomosis of the bypass graft is complete, the heart is resuscitatedand the patient is removed from CPB.

[0006] Although CABG surgery grafts have good long patency rates ofabout 60% to 90% over a ten year period, the isolation of the heart withthe CPB and aortic cross-clamp carries a significant risk of mortality.It is believed that three critical determinants which affect outcomes ofCABG surgery are: (1) time the patient spends on bypass, (2) time thepatient spends with a clamped aorta, and (3) the quality of theanastomoses. It is generally believed that a CABG patient's operativeand peri-operative morbidity are directly related to how long thepatient must be on CPB. During prolonged periods on CPB, there is agreater chance for air and platelet embolization resulting from theartificial circuit. For example, such debris can embolize into theneurovasculature and potentially cause a stroke. In analyzing the timingof individual CABG steps against the backdrop of a patient's criticaltime on CPB, the time spent anastomosing the grafts to vessels emergesas a controlling factor. Closely related to the time spent on CPB is asecond CABG success factor related to the extent and time of aorticcross-clamping. It is believed that the inherent crushing force from across-clamp across the bridge of the muscular aortic arch may beassociated with a high degree of tissue trauma and structural damage.Additionally, blood clots formed at or adjacent to the cross clamp,perhaps in conjunction with the tissue trauma of clamping, may also be asource of unwanted complications. In addition to the potential clinicalcomplications associated with CABG surgery is also the cost of thetime-consuming procedure.

[0007] In the PTCA procedures, a small incision is made in the patient'sthigh to introduce a catheter into the femoral artery. The catheter isguided to the internal blockage site via x-ray visualization. Theblockage is then treated remotely by use of hydraulic pressure in thecase of balloon angioplasty wherein a balloon is inflated within thenarrowed vessel to stretch or otherwise deform the blockage into alarger lumen. Or, in the case of atherectomy, other actuating means canbe used to cause remote cutting or ablation of the blockage. In anotherapproach, a stent is used to scaffold open the blocked area of theartery. Although these procedures are less traumatic than CABG surgery,the failure rate is often about 30-50% whereby the vessel narrows withina six month period and must be treated again.

[0008] Due to the limitations with these operative techniques, alternatemethods have been proposed. For example, U.S. Pat. No. 5,655,548 byNelson et al. discloses open surgical and transluminal methods forsupplying long-term retrograde perfusion of the myocardium via a conduitdisposed between the left ventricle and the coronary sinus. Bloodejected from the left ventricle enters the coronary sinus during cardiacsystole. The outlet from the left ventricle to the coronary sinus mayinclude a one-way valve to prevent backflow from the coronary sinus intothe left ventricle during cardiac diastole. The long-term artero-venousfistula that is created, however, has the potential for edema or otherphysiologic effects.

[0009] Another alternate method is disclosed in international patentapplications: WO 97/27897, WO 97/27893, WO 97/13463, WO 97/13471, and WO97/27898; wherein a percutaneous, transluminal approach is describedwhich requires an adjacent cardiac vein to perform the procedure.Unfortunately, most coronary arteries do not have adjacent cardiac veinsand, thus, the disclosed approach may be limited in its ability toprovide full revascularization.

[0010] Another method is disclosed by Wilk in U.S. Pat. Nos. 5,429,144,5,287,861, 5,662,124 and 5,409,919, wherein an expandable stent isdisposed in the myocardium by a percutaneous approach through thecoronary artery requiring no incision through the chest. The methodrequires that the expandable stent be initially collapsed, ejected froma catheter into the myocardium, and subsequently expanded with aninflatable balloon in the myocardium. The expandable stent extends onlypartially through the myocardium, from the left ventricle of the heartor from a coronary artery, upstream of a vascular obstruction.Alternatively, the expandable stent can extend through the myocardiumbetween the left ventricle and the coronary artery, but is completelywithin the myocardium and not extending into either the left ventricleor coronary artery. The purpose of the expandable stent is to establishblood flow to the myocardium, and in some instances, to the coronaryartery. One design of the expandable stent is to collapse and closeduring systole. In an alternate design, the expandable stent can resistthe contractive pressure of the heart to remain open during systole topermit the flow of blood through the stent into the myocardium andcoronary artery. During diastole, the blood pumped into the coronaryartery through the expandable stent can be blocked from returning to theleft ventricle by an integrated, one-way valve.

[0011] Among the drawbacks in using the Wilk method is that the stentmust be expandable and any valve therein must be integral with thestent. The expandable stent is also sized to be only within, and notbeyond, the myocardium. The expandable stent fails to accommodatechanges in the thickness of the myocardium wall during the rhythmiccontraction of the heart which, according to Feigenbaum's textbook ofEchocardiography, changes from an average thickness of about 8 mm indiastole to about 13 mm in systole. The transluminal approach disclosedby Wilk can also have difficulty in delivering the expandable stentacross coronary arteries which are substantially occluded. Approximately60% of CABG surgery procedures are performed on totally occluded vesselswhere percutaneous access would not be feasible.

[0012] Ever since the discovery by Wearn, as reported in the “The Natureof the Vascular Communications Between the Coronary Arteries and theChambers of the Heart”, American Heart Journal, Volume 9, Number 2,1933, that the myocardium is composed of a vast, sinusoidal network,people have attempted to revascularize the heart muscle directly. In1957, Massimo and Boffi reported experiments in the Journal of ThoracicSurgery, Volume 34, Number 2, with T-shaped tubes that were implanteddirectly into the myocardium in order to maintain a fluid channelbetween the left ventricle and myocardium. Another approach pioneered byVineberg, “Coronary Vascular Anastomoses by Internal Mammary ArteryImplantation”, Canad. M. A. J., Volume 78, Jun. 1, 1958, focused on theimplantation of the IMA directly into the myocardium. In 1965, Sen etal., “Transmyocardial Acupuncture”, Journal of Thoracic andCardiovascular Surgery, Volume 50, Number 2, 1995, performedtransmyocardial acupuncture which became the precursor to laser-assistedtransmyocardial revascularization (TMR) in 1986, wherein multiple laserpin holes are made in the compromised myocardial area and into the leftventricle. However, these holes do not maintain a channel between theleft ventricle and the native coronary circulation. Also, these holesare not maintained in an open state once they are formed. It is surmisedthat the benefit of the TMR approach is that it stimulates angiogenesis(new vessel growth) rather than maintaining new channels of perfusion.

[0013] There have been several studies that clearly teach away from thetransmyocardial arterial revasculation described in the presentinvention. In a study similar to Sen et al., the authors Pifarre et al.,reported in “Myocardial Revascularization by TransmyocardialAcupuncture: A Physiologic Impossibility”, Journal of Thoracic andCardiovascular Surgery, Volume 58, Number 3, 1969, attempts torevascularize the myocardium by coring out sections of the muscle tocreate a left ventricle to myocardial connection. They concluded that “.. . no blood flow is possible from the ventricle to the myocardium.”

[0014] Another article “The Possibility of Myocardial Revascularizationby Creation of a Left Ventriculocoronary Artery Fistula” by Ian Munroand Peter Allen, Journal of Thoracic and Cardiovascular Surgery, Volume58, Number 1, 1969, discloses an attempt to revascularize an ischemicmyocardium by constructing a fistula between the cavity of the leftventricle and the coronary circulation. Two conclusions drawn from theexperimental results again teach away from the present invention.“First, any attempts to revascularize the wall of the left ventricledirect from the cavity of the ventricle are likely to be functionalfailures, even if technically successful . . . In addition, there was afailure of myocardial contractility and a rise in left ventricular anddiastolic pressure. It was concluded that operations designed torevascularize the myocardium direct from the cavity of the leftventricle make the myocardium ischemic and are unlikely to succeed.”

[0015] While other attempts have been made to reduce the complicationsassociated with “CABG” surgery through less-invasive, standard surgicalapproaches, they have been limited in their ability to fullyrevascularize the heart and provide a comparable degree of long-termsuccess. The prior art fails to disclose or fulfill the need fortransmyocardial blood flow or coronary revascularization using a beatingheart approach with either surgical or percutaneous techniques to createand maintain one or more regulated channels between the left ventricleand the arterial vascular system of the heart. The present inventionalso potentially eliminates the need for harvesting autologous bypassgraft material that can be in short supply, contributes to the morbidityof the CABG procedure, and can compromise the vascular system.

SUMMARY OF THE INVENTION

[0016] The present invention provides a method for increasing the flowof blood to a selected site in a patient's arterial vascular system ofthe heart. The method includes the steps of: creating a channel forblood flow from an oxygenated blood source to the selected site in thearterial vascular system of the heart; maintaining the channel in anopen position for blood flow through diastolic and systolic cycles ofthe heart; and regulating the blood flow in the channel to minimizeblood flow from the coronary vascular system to the blood source duringdiastolic cycle of the heart.

[0017] The present invention also provides a method for performing atransmyocardial coronary revascularization procedure for the treatmentof coronary atherosclerosis caused by an obstruction in the arterialvascular system. The method includes the steps of: creating a channelfor blood flow from an oxygenated blood source to the arterial vascularsystem distal to the area of obstruction; maintaining the channel in anopen position for blood flow through the diastole and systole cycles ofthe heart; and regulating the blood flow in the channel to minimizeblood flow from the arterial vascular system to the blood source duringthe diastolic cycle of the heart.

[0018] A method for treating an obstruction in a patient'scardiovascular system using a non-expandable conduit made ofbiocompatible material is also provided by the present invention. Themethod includes the steps of: inserting the conduit completely throughthe myocardium of the patient's heart with one end of the conduitextending into the left ventricle and the other end of the conduitextending into the arterial vascular system distal to the area ofobstruction; maintaining the conduit in an open position for blood flowthrough the diastolic and systolic cycles of the heart; and regulatingthe blood flow in the channel to minimize blood flow from the arterialvascular system to the left ventricle during the diastolic cycle of theheart.

[0019] Another method provided by the present invention increases theflow of blood to a selected site in a patient's arterial vascularsystem. The method includes the steps of: inserting one end of a conduitinto the left ventricle; inserting the second end of the conduit intothe arterial vascular system at the selected site; maintaining theconduit in an open position for blood flow through the diastolic andsystolic cycles of the heart; and regulating the blood flow in theconduit to minimize blood flow from the arterial vascular system to theleft ventricle during the systolic cycle of the heart.

[0020] The present invention also includes conduits for maintaining achannel between an oxygenated blood source and a site in the arterialvascular system of the heart selected for delivering an increase ofblood flow thereto. The conduit includes a tubular body having an inletend and outlet end between the blood source and selected site,respectively. Preferably, the conduit includes means for regulating theflow of blood between the blood source and selected site. The conduitcan include means for retaining the conduit in the myocardium with theinlet end extending into the left ventricle. Optionally, the conduitincludes means for adjusting the conduit to the change of thickness ofthe myocardium during the heart cycle.

[0021] The present invention also provides a self-maintained channelcreated between an oxygenated blood source and a site in the arterialvascular system of the heart selected for delivering an increase ofblood flow thereto. The self-maintained channel maintains an openposition during at least a portion of the heart cycle. Theself-maintained channel includes an inlet end and outlet end between theblood source and selected site, respectively. Preferably, theself-maintained channel includes an integral means for regulating theflow of blood between the blood source and selected site. Optionally,the self-maintained channel includes a natural or synthetic valvepositioned therein as the regulating means.

BRIEF DESCRIPTION OF THE DRAWING

[0022]FIG. 1 is a schematic cross-sectional view of a human heartshowing a conduit inserted by a surgical method into a channel createdfrom the left ventricle to a coronary artery in accordance -with thepresent invention;

[0023]FIG. 2 is a side view of another embodiment of the needle assemblyillustrated in FIG. 1 for creating and dilating an access port in themyocardium or other tissue layer in accordance with the presentinvention;

[0024]FIG. 3 is a side view of a delivery assembly for inserting aconduit into the myocardium or other tissue layer in accordance with thepresent invention;

[0025]FIG. 4 is a schematic cross-sectional view of a human heartshowing a conduit inserted by a surgical method into a channel createdfrom a coronary artery to the left ventricle in accordance with thepresent invention;

[0026]FIG. 5 is an integrated assembly to perforate, dilate, and inserta conduit into a channel in the myocardium or other tissue layer inaccordance with the present invention;

[0027]FIG. 6 is a schematic cross-sectional view of a human heartshowing a conduit inserted by a surgical method into a channel createdfrom a coronary artery and the left ventricle in accordance with thepresent invention;

[0028]FIG. 7 is another embodiment of an integrated assembly toperforate, dilate, and insert a conduit into a channel in the myocardiumor other tissue layer in accordance with the present invention;

[0029]FIG. 8 is a schematic cross-sectional view of a human heartshowing a conduit inserted by a surgical method into a channel createdfrom a coronary artery, both distal and proximal to a blockage, and tothe left ventricle in accordance with the present invention;

[0030]FIG. 9 is a schematic cross-sectional view of a human heartshowing a conduit inserted by a surgical method into a channel createdalong an extended portion of the myocardium from a coronary artery, bothdistal and proximal to a blockage, and to the left ventricle inaccordance with the present invention;

[0031]FIG. 10 is a schematic cross-sectional view of a portion of thehuman heart showing a conduit inserted by a surgical method into achannel created from a coronary artery to a coronary vein and into theleft ventricle in accordance with the present invention;

[0032]FIG. 11 is a schematic cross-sectional view of a portion of thehuman heart showing a conduit inserted by a surgical method into achannel created from a coronary vein into both a coronary artery and theleft ventricle in accordance with the present invention;

[0033]FIG. 12 is a schematic cross-sectional view of a portion of thehuman heart showing a conduit inserted by a surgical method into achannel created from a coronary artery, both distal and proximal to ablockage, through a coronary vein and into the left ventricle inaccordance with the present invention;

[0034]FIG. 13 is partial cross-sectional view of a conduit positionedwithin the myocardium in accordance with the present invention;

[0035]FIG. 14 is a schematic cross-sectional view of a human heartshowing a conduit inserted by a percutaneous method into a channelcreated from the left ventricle to a coronary artery in accordance withthe present invention;

[0036]FIG. 15 is a schematic cross-sectional view of a human heartshowing a conduit inserted by a percutaneous method into a channelcreated from a coronary artery to the left ventricle in accordance withthe present invention;

[0037]FIG. 16 is an integrated assembly to percutaneously perforate,dilate, and insert a conduit into a channel in the myocardium or othertissue layer in accordance with the present invention;

[0038]FIG. 17 is a schematic cross-sectional view of a portion of thehuman heart showing a conduit inserted by a percutaneous method into achannel created from a coronary artery to a coronary vein and into theleft ventricle in accordance with the present invention;

[0039]FIG. 18 is a schematic cross-sectional view of a portion of thehuman heart showing a conduit inserted by a percutaneous method into achannel created from a coronary artery into a coronary vein distal tothe channel into the left ventricle in accordance with the presentinvention;

[0040]FIG. 19 is a schematic cross-sectional view of a portion of thehuman heart showing a conduit inserted by a percutaneous method into achannel created from a coronary artery, both distal and proximal to ablockage, through a coronary vein and into the left ventricle inaccordance with the present invention;

[0041]FIG. 20 is a cross sectional view of an embodiment of the valvedconduit having projections as retaining means in accordance with thepresent invention;

[0042]FIG. 21 is a cross sectional view of another embodiment of thevalved conduit having projections as retaining means in accordance withthe present invention;

[0043]FIG. 22 is a cross sectional view of an embodiment of the valvedconduit having a thread as retaining means in accordance with thepresent invention;

[0044]FIG. 23 is a cross sectional view of an embodiment of the valvedconduit having a flared end as retaining means in accordance with thepresent invention;

[0045]FIG. 24 is a cross sectional view of an embodiment of the valvedconduit having a coating as retaining means in accordance with thepresent invention;

[0046]FIG. 25 is a cross sectional view of an embodiment of the valvedconduit having slots as retaining means in accordance with the presentinvention;

[0047]FIGS. 26A and 26B are cross sectional views of the myocardiumchanging thickness along a conduit during systole and diastole,respectively, in accordance with the present invention;

[0048]FIG. 27 is a cross sectional view of an embodiment of the valvedconduit having telescoping sections as adjusting means in accordancewith the present invention;

[0049]FIG. 28 is a cross sectional view of an embodiment of the valvedconduit having telescoping sections as adjusting means in accordancewith the present invention;

[0050]FIG. 29 is a cross sectional view of an embodiment of the valvedconduit having an accordion section as adjusting means in accordancewith the present invention;

[0051]FIG. 30 is a cross sectional view of an embodiment of the valvedconduit having a lateral accordion section as adjusting means inaccordance with the present invention;

[0052]FIG. 31 is a cross sectional view of an embodiment of the valvedconduit having a coil as adjusting means in accordance with the presentinvention;

[0053]FIG. 32 is a side view of an embodiment of the conduit having abranch configuration in accordance with the present invention;

[0054]FIG. 33 is a side view of an embodiment of the conduit having ahook configuration in accordance with the present invention;

[0055]FIG. 34 is a side view of an embodiment of the conduit having ahybrid synthetic/natural configuration in accordance with the presentinvention;

[0056]FIG. 35 is a cross sectional view of a vein used as a valve inaccordance with the present invention;

[0057]FIG. 36 is a cross sectional view of another embodiment of a veinused as a valve in accordance with the present invention;

[0058]FIG. 37 is a cross sectional view of a valve in accordance withthe present invention;

[0059]FIG. 38A and FIG. 38B are side views of a conduit regulating bloodflow during two phases of the heart cycle in accordance with the presentinvention;

[0060]FIG. 39 is a cross sectional view of a valve in a self-maintainedchannel in the myocardium in accordance with the present invention;

[0061]FIG. 40 is an isolated front view of the valve in FIG. 39;

[0062]FIG. 41 is a cross sectional view of a self-maintained channel inthe myocardium in accordance with the present invention; and

[0063]FIG. 42 is a cross sectional view of a self-maintained channel inthe myocardium in accordance with the present invention.

DETAILED DESCRIPTION OF THE INVENTION

[0064] The present invention generally describes a transmyocardialapproach wherein one or more new channels, which are preferably aboutthe size of a coronary artery, are formed between the left ventricle orother oxygenated blood source and one or more sites in the arterialvascular system of the heart selected for increasing the flow of bloodthereto. Preferably, the selected site is in a position distal to one ormore obstructed areas within the coronary circulation. The channel iscreated by penetrating completely through the tissue defining the bloodsource, such as the myocardium which defines the left ventricle, or thevascular tissue, which defines a coronary artery. The channel ismaintained in an open state, by mechanical means or through tissueremoval, in order for blood to flow through during the cycle of theheart. The channel is regulated or valved controlling both the directionand/or the quantity of blood flow through the channel between the leftventricle and the selected site in the arterial vascular system of theheart.

[0065] The present invention includes several methods for creating andmaintaining a channel in the myocardium for the purposes of connectingan oxygenated blood source to the arterial vascular system of the heart,compromised by a coronary blockage. The inventive methods include bothsurgical and percutaneous approaches. Generally, the surgical approachesinclude direct access to the exterior of the patient's heart via a chestor thoracic approach. The percutaneous approaches include a minimallyinvasive technique using catheters or other devices which are insertedinto the patients' vessels or heart at a remote access site and guidedto the internal blockage site via visualization by instrumentation. Therevascularization is then accomplished remotely.

[0066] As defined herein, the term diastole refers to the normalrhythmical relaxation of the heart chamber, especially the ventricles,during which they fill with blood. The term systole refers to therhythmic contraction of the heart, especially the ventricles, duringwhich blood is driven through the aorta and pulmonary artery after eachdiastolic period. The term distal is generally defined as in thedirection of the patient, or away from a user of a device, or in adownstream direction relative to a forward flow of blood. In the contextof a medical device intervention with or through a vascular tissuelayer, distal herein refers to the interior or the lumen side of thevascular tissue layer or wall. Conversely, proximal generally means awayfrom the patient, or toward the user, or in an upstream directionrelative to a forward flow of blood. In the context of a medical deviceintervention with or through a vascular tissue layer, proximal hereinrefers to the exterior or outer side of the vascular tissue layer orwall. The term arterial vascular system of the heart includes, but isnot limited to, the myocardium and coronary arteries.

[0067] Although the present invention is specifically described belowwith regard to the coronary artery, it should be understood that thepresent invention is not so limited and that the description isapplicable to any part of the arterial vascular system of the heart. Forexample and not limitation, the description is applicable to the leftanterior descending artery, the circumflex artery, the right coronaryartery, and their tributaries. The description is also specific withregard to the left ventricle, but is applicable to other oxygenatedblood sources of the arterial vascular system such as the left anteriordescending artery, the circumflex artery, the right coronary artery, andtheir tributaries proximal to any obstruction or blockage.

[0068] A preferred method of the present invention is a surgicalapproach which directly accesses and exposes the outside of thepatient's heart and coronary vascular system 10 through the chest areausing a needle assembly 12 as illustrated in FIGS. 1 and 2. Similarcomponents between the figures herein are denoted by the same referencenumerals. An initial access port 14 in the myocardium is made byadvancing the needle assembly 12 through the myocardium 16 from theexterior side 18 of the myocardium 16 and into the left ventricle 20.Then a second access port 22 in the myocardium is made from the interiorside 24 of the myocardium within the left ventricle 20 and underneaththe coronary artery 26. The needle assembly 12 is advanced through themyocardium 16 from the left ventricle 20 and into the coronary artery 26at a point distal to the lesion or blockage 28.

[0069] After the needle assembly 12 has created the second access port22, a guide wire 30 or other directional means is extended from thedistal end 32 of the needle assembly into the coronary artery 26. Asufficient length of the guide wire 30 is advanced into the coronaryartery 26 to prevent its premature withdrawal. Optionally, the distalend 34 of the guide wire can contain a balloon 36 or other temporaryanchoring means to prevent premature withdrawal of the guide wire 30from the coronary artery. The proximal end 38 of the guide wire extendsthrough the left ventricle 20 to the exterior 18 of the myocardium whereit is available for manipulation by the surgeon. With the guide wire 30extending from the exterior 18 of the myocardium, through the leftventricle 20 and into the coronary artery 26, the needle component 40 ofthe assembly is withdrawn from both the initial and second access ports.

[0070] The method uses the connection made by the second access port 22between the left ventricle 20 and the coronary artery 26 to create andmaintain a channel 42 therebetween. The initial access port 14 isdilated to allow the advancement of a delivery device 44 as illustratedin FIG. 3 having a sheath 46 covering a valved conduit 48. The sheath 46is configured to assist the passage of the valved conduit 48 through theinitial access port 14 without snagging the valved conduit 48 ordamaging the myocardium 16. The delivery device 44 is advanced over theguide wire 30, through the initial access port 14, and into the leftventricle 20. The guide wire 30 directs the delivery device 44 to thesecond access port 22. The valved conduit 48 is then removed from thesheath 46 with a pusher rod 74 and the delivery device 44 inserts thevalved conduit 48 into the second access port 22 so that the valvedconduit 48 extends through the myocardium 16 from the left ventricle 20to the coronary artery 26. The conduit 48 keeps the second access port22 dilated and maintains the channel 42 between the left ventricle 20and the coronary artery 26. The end 50 of the conduit preferably extendsinto the left ventricle 20 during the rhythmic contractions of theheart. It is preferred that the valved conduit end 50 extends into theleft ventricle 20 at least during diastole when the myocardium is at theminimal thickness of its cycle. The other end 52 of the conduit can beapproximately flush with the exterior 18 of the myocardium or extendsslightly into the coronary artery 26 during at least during the diastolewhen the myocardium is at the minimal thickness of its cycle.

[0071] The remainder of the delivery device 44 is then withdrawn fromthe left ventricle 20 through the initial access port 14. Eithersimultaneous with or subsequent to the withdrawal of the delivery device44, the balloon 36 at the distal end 34 of the guide wire is deflated(or the temporary anchor means is retracted) allowing withdrawal of theguide wire 30 from the coronary artery 26 along the valved conduit 48and from the left ventricle 20 through the initial access port 14. Theinitial access port 14 is then sealed with a suture or allowed to sealitself without assistance.

[0072] Referring to FIG. 1, another embodiment of the present inventioneffectively anchors the distal end 34 guide wire by initially continuingto advance the guide wire beyond the coronary artery 26. As shown inphantom, the distal end 34A of the guide wire is advanced through theinterior 70 and exiting from the exterior side 72 of the coronaryartery. The distal end 34A is then exposed for anchoring in position.

[0073] The needle assembly 12 can be of any shape sufficient toperforate and penetrate the myocardium 16 while minimizing tissuedamage. For example, FIG. 1 shows the needle assembly 12 having a curvedshape which can assist in initially penetrating from the exterior side18 of the myocardium and continuing to penetrate the interior side 24 ofthe myocardium underneath the coronary artery 26. Other shapes for theneedle assembly 12 are suitable for use in the present invention whichcan penetrate and can depend upon the particular surgical approach to beused. For example and not limitation, FIG. 2 illustrates a straightneedle assembly 12, commonly referred to as a seldinger-type needle. Asuitable diameter for the needle component 40 is about 12 gauge.

[0074]FIG. 2 specifically illustrates more details of the needleassembly 12 other than an alternate shape. Preferably, the needleassembly 12 includes a needle component 40 having at least one lumen 54extending substantially across length of the needle component. The firstlumen 54 can be used to allow blood flow therethrough. As the distal end32 of the needle assembly is advanced from the myocardium exterior 18and enters the left ventricle 20, the blood in the left ventricle 20will travel through the lumen 54 and blood 66 will be visually observedexiting the proximal end 62 of the needle assembly. This bleeding“flashback” 66 is especially prominent during the contraction of theleft ventricle 20. As the distal end 32 of the needle assembly isfurther advanced through the left ventricle 20 to contact the myocardiuminterior 24, the bleeding flashback 66 will subside until the distal end32 of the needle assembly completely penetrates the myocardium 16. Theentry of the distal end 32 of the needle assembly into the coronaryartery 26 will be evidenced by resumption of the bleeding flashback 66through the proximal end 62 of the needle component or some otheraccessing feature. The first lumen 54 is also used to retractably carrythe guide wire 30 therethrough.

[0075] Optionally, the assembly 12 can include a second lumen 56 whichalso extends substantially across the length of the needle component 40.One end 58A of the second lumen is located at the distal end 32 of theneedle component. Alternately, the end 58B of the second lumen islocated at some predetermined distance from the distal end 32 of theneedle component. The other end 60 of the lumen is located near theproximal end 62 of the needle component. As the distal end 32 of theneedle assembly is advanced from the myocardium exterior 18 and entersthe left ventricle 20, the blood in the left ventricle 20 will travelfrom one end 58A or 58B of the second lumen to the other end 60 andblood 66 will be visually observed exiting the proximal end 62 of theneedle assembly.

[0076] The lumen 54 or second lumen 56 and its ends 60 and 58A or 58Bact as marker ports which provide evidence when the distal end 32 of theneedle assembly is first in the left ventricle 20 and subsequently inthe coronary artery 26. Other means for marking the position of thedistal end 32 of the needle assembly are suitable for use with thepresent invention. For example and not limitation, the depth of thepenetration through the myocardium to form the initial and second accessports 14 and 22 can be estimated by conventional diagnostic imagingand/or by reading one or more depth markers 68 placed in predeterminedpositions along the length of the needle assembly 12.

[0077] The needle assembly 12 provides for perforating the myocardium 16to create and access port. The assembly 12 also provides for dilatingthe access port and for ensuring the position of the assembly has beenadvanced into the left ventricle 20 and/or coronary artery 26.

[0078] Another inventive method is a surgical approach which gainsaccess to the exterior of the patient's heart illustrated in FIG. 4through conventional cardiac surgical methods. Using the needle assembly12 as previously described in FIG. 2, an initial access port 76 is madein the coronary artery 26 distal to the point of the obstruction 28. Theneedle assembly 12 is advanced into and through the coronary artery 26to contact the exterior 18 of the myocardium underneath the coronaryartery 26. The needle assembly 12 is further advanced to penetrate themyocardium 16 and make an access port 78 in the myocardium whileeventually entering the left ventricle 20. The needle assembly 14extends into the left ventricle 20 to the extent that flashback bleeding66 is observed to assure the myocardium 16 has been completelypenetrated.

[0079] After the needle assembly 12 has created the second access port22, a guide wire 30 or other directional means is extended from thedistal end 32 of the needle assembly into the left ventricle 20. Asufficient length of the guide wire 30 is advanced into the leftventricle 20 to prevent its premature withdrawal. Optionally, the distalend 34 of the guide wire can contain an inflatable balloon 36 or othertemporary anchoring means to prevent premature withdrawal of the guidewire 30 from the left ventricle 20. With the guide wire 30 extendingfrom the left ventricle 20 to the exterior 18 of the myocardiumunderneath the coronary artery 26, through the interior 70 of thecoronary artery and to the exterior 72 of the coronary artery, theneedle component 40 of the assembly is withdrawn from both the accessports 78, 76.

[0080] In another embodiment of this surgical approach wherein theinitial access port 76 is created in the exterior of the coronary artery26, it may be desirable to offset the alignment of the initial accessport shown as 76A from the myocardium access port 78. This can beaccomplished in several ways such as through simple angling of theneedle assembly 12 while creating the access ports or using a needleassembly 12 which is curved or has an offset in its configuration. Theeventual closing of the initial access port 76 may cause trauma to thevascular tissue in that area. Providing an offset in the alignment ofthe access ports 76A, 78 avoids the initial access port area from beingdirectly over or along the path of the blood flow path from the insertedvalved conduit 48.

[0081] Similar to what has been discussed before, the access port 78 inthe myocardium is dilated to accommodate the delivery of a valvedconduit 48 therein. Inserting the valved conduit 48 into the access port78 creates and maintains by mechanical means a channel 42 through themyocardium from the left ventricle 20 to the coronary artery 26. Thedelivery of the valved conduit 48 can be effectuated by inserting aguide wire 30, withdrawing the needle assembly 12, directing a deliveryassembly 44 as seen in FIG. 3 containing the valved conduit 48 over theguide wire 30 through the initial access port 76 to the access port 78,dilating the access port 78, inserting the valved conduit 48 into theaccess port 78, and withdrawing the delivery assembly 44 and guide wire30 from the left ventricle 20 and coronary artery 26. Subsequently, theinitial access port 76 on the exterior 72 of the coronary artery isclosed by stitches, staples, or other closure means.

[0082] An alternate embodiment of the present invention employs a needleassembly and delivery assembly which are integrated so that the guidewire is eliminated. The integrated assembly provides sufficient dilationof the respective access ports to deliver the valved conduit therein.For example, as illustrated in FIG. 5, an integrated assembly 80includes a perforating distal end 82 with a series of gradations orsteps 84 for gradually dilating the respective access port as theintegrated assembly 80 is further advanced. The steps 84 can bepre-formed or result from a retractable telescoping of the body 86 ofthe integrated assembly which can gradually vary its diameter. Thevalved conduit 48 is then removed from the body 86 with a pusher rod 88and the integrated assembly 80 inserts the valved conduit 48 into theaccess port 78 so that the valved conduit 48 extends through themyocardium 16 from the left ventricle 20 to the coronary artery 26. Theconduit 48 keeps the access port 78 dilated and maintains the channel 42between the left ventricle 20 and the coronary artery 26.

[0083] Still another inventive method is a surgical approach which gainsaccess to the exterior of the patient's heart and coronary vascularsystem 10 illustrated in FIG. 6 through conventional cardiac surgicalmethods. Using a first integrated needle/delivery assembly 90, an accessport 92 is created through the myocardium 16 from the exterior side 18into the left ventricle 20. Similar to the previous description herein,the distal end 98 of the integrated needle assembly perforates themyocardium and the myocardium access port 92 is dilated to accommodatethe delivery of one end 96 of the valved conduit 94 which is advancedinto the myocardium access port 92. Inserting the end 96 of the valvedconduit into the myocardium access port 92 creates and maintains achannel through the myocardium 16 from the left ventricle 20 into oneend 96 of the valved conduit.

[0084] Using a second needle/delivery assembly 100, an artery accessport 102 is made in the exterior side 72 of the coronary artery. Withsurgical access to the artery access point 102, the second integratedneedle/assembly 100 can immediately dilate the artery access port 102and insert the other end 104 of the valved conduit after the integratedneedle/delivery 100 perforates the coronary artery 26. Inserting theother end 104 of the valved conduit into the artery access port 102creates and maintains a channel 42 from the left ventricle 20 into oneend 96 of the valved conduit, out the other end 104 of the valvedconduit, and into the coronary artery 26.

[0085] The first needle/delivery assembly 90 is more specificallyillustrated in FIG. 7 which includes a body 106 made of a flexiblematerial. The body 106 is perforated along its longitudinal axis to formseams 108. The valved conduit 94 extends along the longitudinal axis ofthe body 106 with the end 96 of the valved conduit positioned near thedistal end 98 of the assembly and the other end 104 of the valvedconduit exiting from the proximal end 110 of the assembly. Once theassembly 90 has perforated and dilated the myocardium access port 92,gripping the other end 104 of the valved conduit exiting from theassembly 90 can be helpful in either advancing the end 96 of the valvedconduit into the myocardium access port 92 or holding the end 96 of thevalved conduit within the myocardium access port 92 as the remainder ofthe assembly 90 is withdrawn. To ease the withdrawal of the assembly 90from the myocardium access port 92, the perforations are broken apart tosplit the seams 108 and the longitudinal sections 112 and 114 of thebody 106 are peeled away leaving the end 96 of the valved conduit in themyocardium access port 92.

[0086] In one alternate embodiment of the type of valved conduit thatcan be used with this surgical approach, the valved conduit 94 can havetwo separate conduit sections wherein a first conduit section 118 isinserted in the myocardium access port 92 and a second conduit section119 is inserted in the artery access port 102. Subsequently, the twosections are connected together to form a continuous channel for theblood flow from the left ventricle 20 to the coronary artery 26. Thevalve 116 can be integrally positioned in either the first or secondconduit section. Or, the valve 116 can be a separate piece from the twoconduit sections wherein each conduit section connects to opposite sidesof the valve.

[0087] In another embodiment of this surgical approach, delivery ofeither end 96 or 104, or both ends, of the valved conduit 94 can beeffectuated by inserting a guide wire through a needle assembly asillustrated in FIG. 2 into the left ventricle 20, withdrawing the needleassembly, directing a delivery assembly as illustrated in FIG. 3containing the valved conduit 94 over the guide wire to the myocardiumaccess port 92, dilating the myocardium access port 92, inserting oneend 96 of the valved conduit into the myocardium access port 92, andwithdrawing the delivery assembly and guide wire from the left ventricle20.

[0088] A further inventive method is a surgical approach which directlyaccesses and exposes the outside of the patient's heart and coronaryvascular system illustrated in FIG. 8. Using a first needle/deliveryassembly 120 of similar design to the one illustrated in FIG. 7, amyocardium access port 122 is made in the myocardium 16 from theexterior side 18 into the left ventricle 20. The myocardium access port122 is dilated to accommodate the delivery of a first input end 124 of aY-shaped, multi-branched valved conduit 126 therein. Inserting the firstinput end 124 of the valved conduit into the myocardium access port 122creates and maintains a channel 148 through the myocardium 16 from theleft ventricle 20 into a first input end 124 of the conduit.

[0089] Using a second needle/delivery assembly 128, a distal arteryaccess port 130 is made in the exterior side 72 of the coronary arteryat a point distal to the lesion or blockage 28. With surgical access tothe distal artery access port 130, the second assembly 128 canimmediately dilate the distal artery access port 130 and insert anoutput end 132 of the multi-branched conduit after the second assembly128 perforates the coronary artery 26.

[0090] Using a third needle/delivery assembly 134, a proximal arteryaccess port 136 is made in the exterior side 72 of the coronary arteryat a point proximal to the obstruction or blockage 28. With the surgicalaccess to the proximal artery access point 136, the third assembly 134can immediately dilate the proximal artery access port 136 and inserts asecond input end 138 of the multi-branched conduit after the thirdassembly 134 perforates the coronary artery 26. Inserting the firstinput end 124 of the multi-branched conduit into the myocardium accessport 122 and the second input end 138 of the multi-branched conduit intoproximal artery access port 136 creates and maintains two channels 140and 142 from two different blood sources, namely the left ventricle 20and the coronary artery 26 proximal to the blockage 28, into the outputend 132 of the multi-branched conduit and into the coronary arterydistal to the blockage 28.

[0091] Preferably, a multi-branch, valved conduit 126 is used having atleast two branches 140 and 142 with valving means 144 located in branch140. With access afforded by this surgical approach, the two input ends124 and 138 and output end 132 of the valved conduit each can beinserted similar to the previous description of FIGS. 6 and 7 withoutthe assistance of remote guidance which avoids using a guide wire or thelike through the interior of the conduit.

[0092] In an alternate embodiment of this surgical approach, each branch140 and 142 of the conduit can initially be a separate component whichcan be connected together after the two input ends and output end havebeen inserted into the myocardium and the coronary artery proximal anddistal to the blockage. The valving means 144 minimizing blood flow intothe left ventricle is located in the branch 140 leading from themyocardium 16 between the first input end 124 and the connection to thesecond input end 138 and the output end 132. Alternately, the valvingmeans 144 can be located near the distal artery port 130 as shown inphantom as 148. Optionally, a second valving means 146 for minimizingblood flow into the proximal coronary artery can be located in branch142 leading from the proximal coronary artery between the second inputend 138 and the connection between the first input end 124 and theoutput end 132. A second valving means 146 is particular useful if thereis a valving means located near the distal artery port 130.

[0093] It should be understood that portions of different approaches canbe combined. For example, a portion of the surgical approach describedin FIG. 8 can be used to connect the proximal and distal coronary artery26 with a channel like branch 142 external to the heart. Instead ofproviding another external channel like branch 140 to connect the leftventricle 20 with the distal coronary artery 26, a surgical approach asdescribed in FIGS. 1 or 4 can provide an internal channel like 42 (FIGS.1 or 4) positioned through the myocardium 20. As a result, blood flowfrom the left ventricle 20 arrives to the distal coronary 26 by aninternal channel like 42 and from the proximal coronary artery throughexternal channel like 142.

[0094]FIG. 9 illustrates another embodiment of a surgical approach whichdirectly accesses and exposes the outside of the patient's heart andcoronary vascular system 10 for the placement of a valved conduit 150through an extended portion along, or at an obtuse angle through, themyocardium 16 rather than taking the shortest path roughlyperpendicularly through the myocardium. Using a first needle/deliveryassembly 154, proximal artery access port 156 is made on the exteriorside 72 of the coronary artery. The assembly 154 is advanced through theinterior 70 of the coronary artery and along the myocardium beforeeventually creating an access port 160 to the left ventricle 20 throughthe myocardium 16. The proximal artery access port 156 and leftventricle access port 160 are dilated to accommodate the delivery of onebranch 162 of the valved conduit 150 so that the valved conduit 150 ispositioned at least partially along the myocardium and is preferablysubjected to the movement created by the rhythmic contractions of thebeating heart.

[0095] Using a second needle/delivery assembly 166, a distal arteryaccess port 168 is created through the coronary artery 26 at a pointdistal to the lesion or blockage 28 into the exterior side 18 of themyocardium to connect with or near the left ventricle access port 160.The second assembly 166 can immediately dilate the distal artery accessport 168 and insert the other branch 164 of the valved conduit into thecoronary artery 26. As a result, the valved conduit 150 has two branches162, 164 which traverse the myocardium 16 at an obtuse angle. The valvedconduit 150 exhibits a substantially greater length compared toperpendicularly traversing the myocardium between the left ventricle 20and coronary artery 26.

[0096] Although the valved conduit 150 can have a solid, rigid design,it is preferred in this embodiment to advantageously use the movementcreated by the rhythmic contractions of the beating heart to provide theregulation of the blood flow from the left ventricle 20 to the coronaryartery 26 distal to the blockage 28. Accordingly, it is preferred that asubstantial length the valved conduit 150 be made of a flexible materialwhich allows the walls 152 of the valved conduit to flex with therhythmic contractions of the beating heart and assist in the regulationof blood flow. The flexing of the conduit walls 152 can occur in severalways such as compression of its diameter or the lateral collapse of theconduit walls 152 upon themselves. It may be desirable to providerigidity to the conduit walls 152 in the area of the valve 158 locatednear the access port 160 to preserve the integrity of the blood flowregulation by the conduit. It should be noted that the branches do nothave to be connected and terminate at one access port 160. A secondaccess port to the left ventricle is also suitable, so that each branch162, 164 has a separate access port to the left ventricle 20.

[0097] Alternately, it is suitable to remove the valve 158 as a distinctcomponent of the conduit by allowing the conduit walls 152 to flex bycollapsing opposing walls against each other to provide the appropriatedegree of closure during diastole. It may also be desirable to providefor regulating blood through both branches by locating the valve 158only in branch 162. Examples of the proper alignment of the valvedconduit 150 traversing the myocardium 16 are described in more detailbelow.

[0098] Other means of positioning the valved conduit 150 along a moreextensive path between the left ventricle 20 and coronary artery 26 aresuitable for use in the present invention. For example and notlimitation, the direct access to the exterior of the heart 10 allows atrough to be excised between the left ventricle access port 160 and thedistal artery access port 168. The left ventricle access port 160 can becreated at one end of the trough and the distal artery access port 168at the other end of the trough. One end of the valved conduit 150 isthen positioned into the left ventricle and extends within the trough tothe other end of the valved conduit which is inserted into coronaryartery 26 as previously described therein.

[0099] Although the position of the valved conduit 150 is specificallyillustrated as traversing the myocardium along an extended path orobtuse angle, it should be noted that the present invention is not solimited. The valved conduit 150 can be positioned partially or whollywithin the myocardium including other tissue layers enveloping the hearti.e. pericardium, epicardium, endocardium, etc., or external to theheart and vascular system, or in a combination thereof.

[0100] Another embodiment of the surgical approach using the valvedconduit at least partially positioned within the myocardium is toutilize a valved conduit with only one branch similar to the methodsillustrated in FIGS. 1, 4 and 6. Optionally, other branches are added tothe valved conduit 150 of FIG. 9 to connect to other sources ofoxygenated blood, namely another coronary artery, or to deliver theoxygenated blood to multiple ischemic areas. Each additional branch canbe positioned across the myocardium along an extended path or obtuseangle as described above or in a perpendicular direction across themyocardium.

[0101]FIG. 10 illustrates another embodiment of a surgical approachwhich directly accesses and exposes the outside of the patient's heartand coronary vascular system 10 for the placement of a valved conduit180 across the myocardium 16. A needle/delivery assembly 182 creates aninitial access port 184 in the exterior side 72 of the coronary arterydistal to the blockage 28. The assembly 182 is advanced through theinterior 70 of the coronary artery to create an access port 190 throughthe vascular wall 186 of an adjacent coronary vein 188. The assembly 182is then advanced through the coronary vein 188 to create an access port192 in the exterior side 18 of the myocardium and completely through themyocardium 16 into the left ventricle 20. The valved conduit 180 is theninserted into and through the myocardium 16 creating a channel 42directly from the left ventricle 20 to the coronary vein 188. The bloodflow into the coronary vein 188 is limited to a particular area orsection 170 by inserting plugs 194 within the coronary vein proximal anddistal to the access ports 190, 192. The plugs 194 can be moved intotheir respective positions by insertion through the access ports 184,190. Another technique for inserting the plugs 194 is to perforate,dilate, and insert the plugs 194 directly through the exterior side ofthe coronary vein 188 near the area the plugs 194 are desired. Devicesor techniques other than plugs 194 can be used to isolate a section ofthe coronary vein 188 such as by using a suture around the vein in aposition at least proximal to the access ports 190, 192 to close offblood flow to the section.

[0102] A second conduit 196 is inserted into the access port 190 tomaintain a second channel 198 between the coronary artery 26 and thecoronary vein 188. As a result, blood flows during systole from the leftventricle 20 into the coronary vein 188 and subsequently into thecoronary artery 26 distal to the blockage 28. The coronary vein 188 canprovide a temporary reservoir of blood. The valved conduit 180 minimizesbackflow of blood from the coronary vein and artery during diastole.Upon withdrawal of the assembly 182, the initial access port 184 isclosed.

[0103] As illustrated, the conduit 180 can optionally include areservoir connected to it for temporarily storing blood. The reservoirmay be a separate container like the section 170 of the coronary vein188 that is connected to the conduit 180 or a container that isintegrally formed with the surface of the conduit. The reservoir canalso be effectively formed from a material which has the ability toexpand and contract so that it becomes a reservoir during certainperiods of the heart cycle.

[0104] The assembly 182 can be elongated to initially contain both thevalved conduit 180 and the second conduit 196 so that each may berespectively positioned without withdrawing the needle assembly from theinitial access port 184. Other alternates are available, such aswithdrawing the needle assembly 182 to reload with the conduit not firstplaced in position. Or, temporarily dilating the access port 184 withanother device so that a second needle/delivery assembly can be insertedthrough the same access port.

[0105] Although there is only one valved conduit 180 and it ispositioned completely through the myocardium 16, the present inventionincludes several other options for regulating blood flow. For example,one option is to position the valved conduit 180 between the coronaryartery 26 and coronary vein 188 and position the second conduit 196without a valve through the myocardium between the left ventricle 20 andthe coronary vein 188. This arrangement creates a reservoir of bloodwithin the coronary vein 188 which may allow for blood flow into thecoronary artery 26 during diastole.

[0106] Another option positions the valved conduit 180 and secondconduit 196 as illustrated in FIG. 10. However, a valve shown in phantomas 180A is added to the second conduit 196. As a result, the coronaryvein 188 provides a reservoir of blood in section 170 which augmentsblood flow into the coronary artery 26 during diastole. Anotherembodiment of this surgical approach wherein the channel between theleft ventricle and coronary artery is transvascular and transmyocardialas illustrated in FIG. 11. An initial access port 184A is created in thetop exterior of the coronary vein 188 instead of the coronary artery 26.The assembly 182 is advanced to create the access port 190 into thecoronary artery 26, to insert the second conduit 196 and is thenwithdrawn. The assembly is also advanced from the initial access port184A to create the access port 192 into the myocardium 16, insert thevalved conduit 180 and is then withdrawn.

[0107] Alternately, the initial access port 184A is created to advancethe assembly 182 and create an access port from the coronary vein 188 toeither the left ventricle 20 through the myocardium 16 or to thecoronary artery 26, but not both. Another initial access port 184B iscreated with the same or another assembly to complete the remainingaccess port. For example, access port 192 is made through the myocardiumand the alternate access port 184B is used to make alternative accessport 190B into the coronary artery 26. As a result, the alignment of theaccess ports 190B, 192 is offset from one another.

[0108] Although a valved conduit 180 is specifically illustrated inFIGS. 10 and 11, the coronary vein 188 itself can be used to regulatethe flow of blood from the left ventricle 20 into the coronary artery26. In this embodiment, the conduits 180 and 196 need not be valved, butsimply maintain the respective channels. As discussed in more detailbelow, the natural valving function of vascular tissue in the isolatedsection of the coronary vein 188 can be advantageously used to regulatethe flow of blood.

[0109] The present invention includes still another surgical approachwherein transvascular and transmyocardial channels between the leftventricle and coronary artery extend to more than one blood source asillustrated in FIG. 12. An additional initial access port 174A iscreated in the top exterior of the coronary vein 188 at a position whichis proximal to the blockage 28 in the adjacent coronary artery 26. Theassembly 182 is advanced through the interior of the coronary vein 188to create an additional access port 172 for a third channel 178 throughthe exterior wall 72 of an adjacent coronary artery. A third conduit 176is inserted into the additional second access port 172 to maintain thechannel 178. One of the plugs 194 is inserted into the coronary vein 188in a proximal position to the additional initial access port 174A.

[0110] Alternately, the additional initial access port 174B is createdin the top exterior of the coronary artery proximal to the blockage 28.The assembly 182 is then advanced through the interior of the coronaryartery to create the third channel 178 through the exterior wall 186 ofan adjacent coronary vein.

[0111] Another method of the present invention is a surgical approachwhich directly accesses and exposes the outside of the patient's heartand coronary vascular system 10 through the chest area as illustrated inFIG. 13. As described herein, a needle delivery assembly can be used toperforate and dilate an access port 200 in the exterior side 18 of themyocardium so as to insert a valved conduit 204, preferably having ahorizontal branch 208 to form a T-shape, into the left ventricle 20. Thevalved conduit 204 is positioned so that the branch 208 lies within themyocardium and the end 210 of the valved conduit extends within the leftventricle 20. The branch 208 is positioned to lie parallel to themyocardium 16. The valve 212 in the conduit is preferably positionednear the end 210. After insertion of the valved conduit 204, theexterior side 18 of the myocardium is closed by suturing or othersuitable closure means.

[0112] Alternately, an incision can be made along a suitable course inthe exterior side 18 of the myocardium such as along the phrenic nerveinto the vascular area of myocardium 16 above the left ventricle 20 infront of the coronary artery. The incision is deepened almost to theinterior side 24 of the myocardium or the endocardium 202. Optionally, asmall cavity 206 can be created to assist in the placement of theconduit 204. As previously described, a needle assembly is then used toperforate through the endocardium 202 or remaining myocardium below theincision 200, to the left ventricle 20.

[0113] An example of suitable dimensions for the preferred T-shapedvalved conduit 204 is about a 4 mm diameter with a vertical branch 214of about 15 mm and the horizontal branch 208 of about 20 mm long. Thehorizontal branch 208 is provided to divert blood flow into a directionparallel to the myocardium 16 layer. Other designs for the valvedconduit 204 are suitable for use in the present invention. For exampleand not limitation, the valved conduit 204 can be a straight stem orhave a two horizontal branches in a cross shape. The valved conduit 204can be made of a porous material that allows blood flow to emanate fromthe entire length, or selected portions, of the vertical branch 214and/or horizontal branch 208.

[0114] Another preferred method of the present invention is apercutaneous approach which generally introduces a catheter or otherguidance/delivery device into the blood source such as the leftventricle. A catheter 220 is placed into the circulatory system 10 at aremote access site such as the femoral artery and advanced through theaortic valve into the left ventricle 20 as illustrated in FIG. 14. Thecatheter 220 then is directed to the interior side 24 of the myocardium16 underneath the coronary artery 26 where a penetrating or perforatingneedle 222 is delivered and advanced from the left ventricle 20 throughthe myocardium 16 into the coronary artery 26 to create an access port224 therethrough.

[0115] Once the catheter 222 has been guided to the desired location,the perforating needle 222 is exchanged for a valved conduit 226 whichis delivered to the access port 224 and inserted into the myocardium 16.As described above, the valved conduit 226 extends completely throughthe myocardium 16 to create and maintain a channel 42 between the leftvertical 20 and the coronary artery 26 distal to the blockage 28.

[0116] There are several conventional techniques for locating theposition of a catheter 222 in various places in the human body. Forexample and not limitation, the locating means can be an ultrasoundsystem, magnetic resonance imaging, computer aided tomography or anechocardiograph. A fluid or medium such as a dye can be introduced byconventional means into the left ventricle 20 that allows itsidentification by a scanning instrument and provides a background toidentify the location of the guided catheter 222 in relation to thecoronary artery 26 and the left ventricle 20.

[0117] A suitable inventive method using the percutaneous approach isillustrated in FIGS. 15 and 16. A catheter 228 and guide wire 238 areinserted into the coronary artery 26 from a remote access site such asalong the femoral artery. The guide wire 238 is used to cross theblockage 28 and then the catheter 228 is inserted over the guide wireand advanced past the blockage. The catheter 228 includes a body 230having a distal end 232 and proximal end 234 with a window 236. A guidewire 238 assists in guiding the catheter 228 into the desired positionand exchanging a perforating needle 244 and a valved conduit asdiscussed above. The window 236 is rotated for proper orientation sothat the window 236 faces the tissue layer of the coronary artery 26against the exterior side 18 of the myocardium wherein an access port248 is to be created. Optionally, the body 230 includes a balloon 240which can retractably expand against the inner tissue wall of thecoronary artery 26 to hold the window 236 in its proper orientation.

[0118] The body 230 includes a ramp 242 which directs the perforatingneedle 244 on a wire into the tissue layer to create the access port248. Preferably, the wire 238 has a hole in its center to provide forback bleeding as means of evidencing the position of the needle 244.Alternately, the scanning instrument can determine the position of theneedle 244 advancement. Subsequently, the ramp 242 directs the insertionof the valved conduit 250 into the created access port.

[0119] Another embodiment of the present invention combines portions ofdifferent percutaneous approaches. As described in FIG. 15, a guide wire238 is inserted into the coronary artery 26 from a remote access sitesuch as along the femoral artery. The guide wire 238 is used to crossthe blockage 28 and is advanced into the left ventricle 20. Using thepath described in FIG. 14, a guide wire is advanced from the same accesssite into the left ventricle and is used to snare the guide wire 238advanced from the coronary artery and retrieve the guide wire 238 backto the remote access site. As a result, the guide wire 238 completes acircuit from the remote access site through the coronary artery, acrossthe myocardium, to the left ventricle and back to the remote accesssite. One or more devices can then be advanced through the leftventricle to the interior side of the myocardium without crossing theblockage in the coronary artery.

[0120] Another inventive method using the percutaneous approach whichadvances a catheter 260 into the coronary artery 26 from a remote accesssite such as along the femoral artery is illustrated in FIG. 17. Oncethe position of the catheter 260 is determined within the coronaryartery 26, a penetrating wire 262 is advanced from the catheter to gofrom the coronary artery and penetrate into an adjacent coronary vein264. An excess amount of the penetrating wire 262 is advanced into thecoronary vein 264 to assist in retaining the penetrating wire within thecoronary vein as the catheter is similarly advanced from the coronaryartery 26 into the coronary vein 264. The position of the catheter 260is then determined in the coronary vein 264 relative to the leftventricle 20. The catheter 260 is directed to orient the perforatingwire 262 towards the myocardium 16 underneath the coronary vein 264 andto the left ventricle 20.

[0121] The perforating wire 262 creates an initial access port 268through the vascular wall 272 of the adjacent coronary vein 264 and asecond access port 270 in the exterior side 18 of the myocardium andcompletely through the myocardium 16 into the left ventricle 20. Avalved conduit 266 is then inserted into and through the myocardium 16creating a channel 42 directly from the left ventricle 20 to thecoronary vein 264. The blood flow into the coronary vein 264 is limitedto a particular area or section 286 by inserting plugs 274 within thecoronary vein on both sides of the initial and second access ports 268,270. The plugs 274 can be moved into their respective positions byinsertion through the initial access port 268.

[0122] A second conduit 276 is inserted into the initial access port 268to maintain a second channel 278 between the coronary artery 26 and thecoronary vein 264. As a result, blood flows during systole from the leftventricle 20 into the coronary vein 264 and subsequently into thecoronary artery 26 distal to the blockage 28. The coronary vein 264 canprovide a temporary reservoir of blood. The valved conduit 266 minimizesbackflow of blood from the coronary vein 264 and artery 26 into the leftventricle 20 during diastole.

[0123] Another embodiment of this method is illustrated in FIG. 18. Theinitial access port 268 is offset in its alignment with the secondaccess port 270A. The catheter 260 is guided to a location either adistance further distal or proximal to the initial access port 268before the second access port 270A is created. FIG. 18 specificallyillustrates a distal position.

[0124] The present invention includes still another percutaneousapproach wherein transvascular and transmyocardial channels between theleft ventricle and coronary artery extend to more than one blood sourceas illustrated in FIG. 19. An additional access port 280 is createdbetween the coronary artery and the adjacent vein 264 proximal to theblockage 28 in the adjacent coronary artery 26. The catheter 260 isadvanced through the interior of the coronary vein 264 to create theaccess ports 268 and 270. A third conduit 282 is inserted into theadditional access port 280 to maintain the third channel 284. One of theplugs 274 is inserted into the coronary vein 264 in a proximal positionto the additional access port 280.

[0125] It should be understood that the present invention provides forcombining portions of different surgical approaches, differentpercutaneous approaches, or a combination of surgical and percutaneousapproaches in one method. For example, a surgical approach can use acatheter in a method similar to that described with reference to FIGS.14-19. After gaining access to the exterior of the patient's heart andcoronary vascular system, the same access area is used to guide thecatheter to the coronary vascular system at a location which issignificantly closer to the heart.

[0126] The present invention provides alternate methods of creating theaccess ports for the surgical and percutaneous approaches describedabove. Instead of dilating the access ports, a section of tissue can beremoved to provide the channel through the myocardium or the vasculartissue. The diameter of the tissue section to be removed is preferablyabout equivalent to or larger than the diameter of the valved conduit tobe inserted.

[0127] For example and not limitation, a section of tissue can beremoved by mechanical means such as by positioning a rotary drill heador punch at the distal end 32 of the needle assembly in FIG. 2 or thedistal end of the delivery device 44 in FIG. 3. As the result, thedilation of the access port is partially or completely obviated.

[0128] Another suitable means for removing tissue is laser energy whichis commonly used in transmyocardial revascularization (TMR) techniqueswith adjustments to make a larger diameter channel than isconventionally used in TMR. A laser can be used with either the surgicalor percutaneous approaches described herein. The surgical approachesprovide adequate space to align the laser from a position external tothe heart and vascular system or the laser can be introduced into theleft ventricle or coronary system and create a channel from the insideextending outward. A laser fiber can be carried by a guided catheter asdescribed in the methods above.

[0129] The tissue removal means of the present invention provideschannels which are self-maintaining. Channels created by the removal oftissue can avoid the use of a conduit to keep or maintain the channelopen. As defined herein, the term self-maintained channel is apassageway through tissue which is open for blood flow from anoxygenated blood source to a selected site during at least a portion ofthe heart cycle, preferably during systole. With a self-maintainingchannel, the regulation of blood is controlled by inserting only avalve, no conduit, into the channel. Or, the self-maintained channel canregulate the flow of blood naturally by orienting the self-maintainedchannel through the myocardium as described herein.

[0130] The conduits and valves of the present invention are made ofnatural vascular tissue or synthetic materials or a combination of both.The synthetic materials are bio-compatible and include metals, alloysand plastics containing one or more polymers. The conventional surgicalpolymers are suitable plastics. Metals or alloys which are not inthemselves bio-compatible can be coated with a bio-compatible metal orplastic. Preferably, the conduit material is non-porous to blood.However, it is suitable to use material porous to blood and stillprovide blood flow completely through the length of the conduit.

[0131] A preferred synthetic conduit 400 is illustrated in FIG. 20having an elongated body 402 with a cylindrical or tubular shape and awall 404 having an exterior surface 406 and an interior surface 408. Thewall 404 defines an interior space 410. The body 402 includes an inletend 412 for receiving blood from the left ventricle or other oxygenatedblood source and an outlet end 414 for delivering the oxygenated bloodto a selected site such as a coronary artery or vein.

[0132] The preferred shape of the cross-section of the body 402 alongits longitudinal axis 416 is circular. Other cross-sectional shapes aresuitable for use by the present invention such as, for example and notlimitation, triangular, rectangular, square, elliptical, oval, and othergeometric or free-form shapes. The cross-sectional size is illustratedas uniform across the length of the body 402. However, thecross-sectional size can vary along the length of the body 402, or taperor flare the body 402 near the ends 412 and 414.

[0133] The diameter of the conduit 400 is preferably not expandable andis inserted into the channel 42 as a predetermined size without the needto expand the diameter of the body 402. The body 402 resists compressiveforces placed on it by the myocardium during the heart cycle to maintainthe channel 42 in the open position. However, the present invention alsoprovides for using conduits with a diameter which is expandable afterinsertion into the myocardium.

[0134] Preferably, the length of the conduit 400 is sized to be longerthan the maximum width the myocardium achieves during the heart cycle.The conduit 400 extends beyond the exterior side 18 and interior side 24defining the myocardium and slightly into the left ventricle 20 andcoronary artery 26. It is suitable to provide the length of the conduit400 so that one end is approximately flush with the interior side 24and/or exterior side 18 of the myocardium.

[0135] The conduit 400 includes projections 418 integrally formed withthe body 402 near the inlet end 412 and outlet 414 means for retainingthe conduit in position once it has been inserted within the myocardium16 or other tissue layer. The projections 418 can have an end 420 whichis barbed or otherwise shaped for slightly penetrating, embedding, orabutting the myocardium 16 in the area surrounding the ends 412 and 414.The connection between the body 402 and the projections 418 includes aspring bias which allows the projections 418 to fold relatively flatagainst the exterior surface 406 of the body while the conduit 400 isbeing inserted into the channel 42 through the myocardium 16 or tissuelayer. The projections 418 then relax to their outwardly extendedposition once the ends 412, 414 of the conduit extend into the leftventricle 20 and coronary artery 26 and are clear of the channel 42. Forexample, the spring bias can be supplied by conventional memory orsuperelastic materials.

[0136] Preferably, the synthetic conduit 400 includes a valve 422 havingflaps 424 which open to allow blood flow in one direction from the leftventricle 20 to the coronary artery 26 and close to minimize thebackflow of blood in the reverse direction. The closure of the flaps 424need not completely seal the interior space 410. The valve 422 can besupported by a ring 426 inserted within the interior space 410 so as toabut the interior surface 408 as a component separate from the body 402.Alternately, the valve 422 can be integrally formed with the wall 404.

[0137] Other examples of retaining means are provided by the presentinvention. For example and not limitation, FIG. 21 illustratesprojections 430 which are initially retracted into the interior space410 through slots 432 in the wall 404. The connection between the body402 and the projections 430 includes a spring bias which allows theprojections 430 to retract into the interior space 410 of the body whilethe conduit 400 is being inserted into the channel 42 through themyocardium 16 or tissue layer. The projections 430 then released totheir outwardly extended position once the conduit 400 is in the desiredposition. This embodiment also illustrates that the projections 430slightly penetrate the face 434 of the channel 42 rather the area of themyocardium surrounding the channel.

[0138] Another example of the retaining means provided by the presentinvention include forming a screw thread 436 on the exterior surface 406of the body as illustrated in FIG. 22. The thread 436 is of sufficientsize and quantity to hold the conduit 400 in the desired position bybiting into the face 434 of the channel. The thread 436 can extend overone or more sections of the exterior surface 406. The thread 436 neednot be continuous and can be positioned anywhere along the length of theexterior surface 406.

[0139] Other examples of the retaining means provided by the presentinvention includes expanding one or both ends of the conduit 400 to adiameter greater than the channel 42. FIG. 23 illustrates the inlet end412 being flared 438 so that its diameter is greater than the diameterof the channel 42. The flared end 438 extends beyond the myocardium 16layer. The end 438 can be flared prior to or after insertion of theconduit 400 into desired position. FIG. 24 illustrates the inlet end 412being effectively expanded by a coating 440 applied to the exteriorsurface 406 of the conduit near the end. The coating 440 expands afterinsertion 440A to hold the conduit 400 in the desired position. Thereare several known plastics or foams which exhibit predictable expansionproperties which are suitable material for use as the coating 440.

[0140] In similar embodiments, an adherence between the exterior surface406 of the conduit and the face of the myocardium along the channel canbe promoted to retain the conduit in the desired position. For example,at least a portion of the length of the conduit 400 can be coated on theexterior surface 406 with a bio-compatible adhesive which assists theadherence with the face of the myocardium. Another example is to abradethe exterior surface 406 of the conduit.

[0141]FIG. 25 illustrates that the retaining or anchoring means can belocated anywhere along the length of the body 482 of the conduit 480such as the middle section 484. Another type of anchoring means is alsoillustrated in the form of elongated slots 486. By having comparablesizes in the diameters of the conduit 480 and the channel, the face ofthe myocardium along the channel may embed into the areas of the slots486 to retain the conduit in the desired position.

[0142] The retaining means can also be useful in sizing the length of aconduit immediately after insertion through the myocardium. For example,using the surgical approach described in reference to FIG. 4, a conduithaving a length significantly longer that the myocardium's maximum widthcan be inserted through the coronary artery and into the myocardium.Preferably, the end of the conduit extending into the left ventricleincludes a retaining means. Once the resistance of the retaining meansis felt by attempting to withdraw the conduit, the excess length of theconduit extending out of the myocardium and through the coronary arteryis cut off.

[0143] The conduit 400 with valve 422 of the present inventionpreferably adjusts to the changing width of the myocardium 16 during theheart cycle. FIGS. 26A and 26B illustrate another example of the conduit400 provided by the present invention wherein the inlet end 412 isflared 438 and the outlet end 414 have projections 442 which slightlypenetrate into the area of the myocardium 16 surrounding the channel 42.During systole, the thickness of the myocardium 16 is near its greatestduring the heart cycle. As illustrated in FIG. 26A, the outlet end 414of the conduit extends slightly into the coronary artery 26 and isretained in positioned by being anchored to the exterior side 18 of themyocardium. The length of the conduit 400 is predetermined so that theinlet end 412 of the conduit also extends slightly into the leftventricle 20 when the myocardium 16 is thickest during the heart cycle.Optionally, the inlet end 412 can be flared 438 so as to further assureretaining the interior side 24 of the myocardium to provide at least aslight extension of the inlet end 412 into the left ventricle 20. Duringdiastole, the thickness of the myocardium 16 decreases. As illustratedin 26B, the outlet end 414 is anchored on one side of the conduitallowing the remainder of the myocardium to slide along the longitudinalaxis 416 of the conduit. The inlet end 412 is not specifically anchoredand is free to extend further into the left ventricle 20 duringdiastole.

[0144] The present invention provides other means for adjusting theconduit 400 to the changing width of the myocardium 16 during the heartcycle. FIG. 27 illustrates the conduit 400 with at least a twotelescoping components 444, 446 which slidably insert into one anotheras indicated by arrow 445. Both the inlet end 412 and the outlet end 414retain the myocardium in the desired position by anchoring the ends withprojections 442 to the interior side 24 and exterior side 18 of themyocardium, respectively. As the heart cycles, the component 446 slideswithin component 444 in a telescoping manner to adjust to the changingthickness of the myocardium. The length of the telescoping components444, 446 are predetermined so that they remain within each other allthrough the heart cycle.

[0145] Other examples of means for adjusting the conduit 400 to thechanging width of the myocardium 16 during the heart cycle include theillustration in FIG. 28 which provides the conduit 400 with an accordionsection 456 which expands and contracts in a longitudinal direction asindicated by arrow 457 while providing resistance against radialcompression. Each end 412 and 414 retain the myocardium in the desiredposition by anchoring the ends with projections 442 to the interior side24 and exterior side 18 of the myocardium, respectively. As the heartcycles as indicated by arrow 452, the two ends 412, 414 move towardseach other during diastole and away from each other during systole withthe accordion section 456 respectively contracting and expanding in alongitudinal direction.

[0146] Alternately, FIG. 29 illustrates another accordion section 458which reversibly expands in a latitudinal direction. Each end 412 and414 retain the myocardium in the desired position by anchoring the endswith projections 442 to the interior side 24 and exterior side 18 of themyocardium, respectively. As the heart cycles, the two ends 412, 414move towards each other during diastole and away from each other duringsystole with the accordion section 458 respectively contracting andexpanding in a latitudinal direction as indicated by arrows 460. Thelatitudinal accordion section 458 not only maintains and regulates bloodflow through the channel, but also provides a temporary reservoir ofblood in the accordion section 458 itself. The valve 422 can be placedat either end 412, 414 or valves placed at both.

[0147] Another example of the adjusting means of the present inventionis illustrated in FIG. 30 wherein the conduit 400 includes at least twocomponents 448, 450 which form a body 402 which is discontinuous. Eachend 412 and 414 retains the myocardium 16 in the desired position byanchoring the ends with projections 442 to the interior side 24 andexterior side 18 of the myocardium, respectively. The valve 422 can beincluded in either component 488 or 450. With the components 448, 450positioned perpendicular to the myocardium width, the two components448, 450 move towards each other during diastole and away from eachother during systole when the heart cycles as indicated by arrow 452.Without support from either component 448, 459, a section 454 of thechannel between the-two components 448, 450 is self-maintained in theopen position.

[0148]FIG. 31 illustrates an example of an adjusting means wherein theconduit 400 includes a body 402 made of a continuous coil 462 whichexpands and contracts along its longitudinal axis to accommodate thechanging thickness of the myocardium 16 during the heart cycle whileresisting radial compression. The outer periphery 464 of the coil 462slides along the face 466 of the myocardium defining the channel 42. Thecoil 464 is anchored to the myocardium 16 at the inlet end 468 andoutlet end 470 by projections 472 which are supported by rings 474connecting to respective ends of the coil 464. As the coil 462 expands,gaps 476 are formed between the outer periphery 464 of individualspirals or the gaps 476 increase in size if the gaps already exist whenthe coil 462 is at its maximum level of relaxation during systole.Should the face 466 of the myocardium adhere to the outer periphery 464of one or more individual spirals, either immediately after insertioninto the channel or as a long-term effect, the remaining spirals provideexpansion by moving along the longitudinal axis.

[0149] The present invention provides conduits with a variety ofconfigurations emphasizing a non-obtrusive, non-traumatic connectioninto the coronary artery. As illustrated in FIG. 32, a T-shaped conduit490 includes a branch 492 allowing the continued flow of blood orprevents the stasis of blood proximal to the conduit in the coronaryartery 26. FIG. 33 illustrates a hook-shaped conduit 494 having aright-angle bend toward the direction of desired blood flow. The outerperiphery 496 of the conduit outlet end can be sized to have thecoronary artery dilated over its edge or can be smaller than thediameter of the coronary artery. FIG. 34 illustrates a hybrid,synthetic/natural conduit 497 which includes a section of vasculartissue 498 attached to a synthetic segment 499. The vascular tissue 498is attached 495 to the wall 493 of the coronary artery by conventionalclosure means such as suturing. In this embodiment, no section of theconduit 497 extends into the coronary artery.

[0150] The present invention also provides a naturally valved conduitsuch as a vein or other vascular tissue which is preferably autologous.A conduit made from the vein can be all natural or include syntheticmaterials in combination with the vein. As illustrated in FIG. 35, apreferred combination conduit 500 combines a vein 502 which is at leastpartially supported by a synthetic cage 504 having an elongated body 506with a cylindrical or tubular shape and longitudinal members 508 havingan exterior surface 510 and an interior surface 512. The cage 504defines an interior space 514. The body 506 includes end members 516connected to the longitudinal members 508. The cage 504 includesprojections 518 which, as previously described, retain the conduit 500in the desired position with the myocardium.

[0151] The vein 502 is extended along the interior surface 512 throughthe interior space 514 of the conduit. The ends 520 of the vein 502 arestretched over end members 516 and back in the reverse direction tosecure the vein 502 to the cage 504. Optionally, a suture can be placedthrough the end 520 and the wall 528 of the vein. The vein 502 definesan inlet end 522 for receiving blood from the left ventricle or otheroxygenated blood source and an outlet end 524 for delivering theoxygenated blood to a selected site such as a coronary artery or vein.

[0152] The present invention regulates the flow of blood through theconduit 500 utilizing the flaps and wall movement of the vein which areinherent, natural properties of the vein 502. The natural valvingfunction of the vein 502 is preserved by allowing the wall 528 of thevein to move towards itself or substantially collapse upon itself asindicated by arrows 526.

[0153] Another embodiment of the combination conduit 500 is illustratedin FIG. 36. The cage 504 includes a second pair of end members 530spaced in a parallel relationship to the end members 516 and connectedto the longitudinal members 508. Each end 520 of the vein 502 isinserted in a press fit between one of the end members 516 and secondend members 530 to secure the vein 502 to the cage 504. Other means ofsecuring the vein 502 to the cage 504 are also suitable such as besuturing the ends 520 of the vein to the end members 516 with acontinuous suture or a plurality of individual sutures. FIG. 36 alsoillustrates another example of positioning the vein 502 along theexterior side 510 of the cage. As indicated in phantom 528A, the wall528 moves toward itself or substantially collapses upon itself topreserve the natural valving of the vein 502.

[0154] The present invention provides other types of valves forregulating the flow of blood through a conduit or a self-maintainedchannel. One valve type, as used in the Examples herein, is similar to aStarling resistor and illustrated in FIG. 37. The conduit 550 includes arigid, elongated body 552 having an inlet end 554 which extends into theleft ventricle 20. The body 552 extends substantially through themyocardium 16. On the outlet end 556 of the body is attached a valve 558having a tubular body 560 made of a pliable material which extends intothe coronary artery 26 distal to the blockage 28. The pliable materialcan be a section of vein. The tubular body 560 is sufficiently flexibleto collapse on itself. During systole, blood flows out of the outlet end556 into the coronary artery. As the cycle of the heart approachesdiastole, the pressure of the blood flowing from the outlet end 556decreases to the point where the pliable body 560 collapses whichminimizes the reverse flow of blood from the coronary artery 26 backinto the left ventricle 20. Optionally, a cage 548 can be inserted intothe coronary artery 26 in the area of the tubular body 560 to assist inpreventing the collapse of the artery in that area.

[0155] Another example of the valves provided by the present inventionis illustrated in FIGS. 38A and 38B. A conduit 560 extends completelythrough the myocardium 16 and slightly into the left ventricle 20 andthe coronary artery 26. The conduit 560 includes at least one segment562 that is made of a pliable material which resists compression bysmall radial forces but which collapses as seen in FIG. 38B during aportion of the heart cycle. The conduit 560 is orientated at an obtuseangle to the interior side 24 and exterior side 18 of the myocardium andto the direction of change in the thickness of the myocardium. Becauseof the conduit's 560 orientation within the myocardium 16, the forcesapplied by the surrounding myocardium as it contracts and relaxes duringthe cycle of the heart change the both the length and diameter of theconduit 560 as generally illustrated in FIG. 38B. As a result, the flowof blood is minimized into the left ventricle 20 during the cycle of theheart.

[0156] As described above, the present invention provides aself-maintained channel 600 defined by a face 602 of the myocardium 16as illustrated in FIG. 39. The channel 600 extends completely throughthe myocardium 16 in a perpendicular direction from the left ventricle20 on the interior side 24 to the coronary artery 26 on the exteriorside 18. The channel 600 is created by removing tissue so that itremains at least partially open during the cycle of the heart.

[0157] Preferably, the self-maintained channel 600 includes a valve 604inserted within the channel as illustrated in FIGS. 39 and 40. The valve604 includes interleaved flaps 606 supported on a body 608. The valve604 is not associated with a conduit. The width of the body 608 ispreferably the minimum size required to provide support and orientationfor the flaps 606 and not particularly to maintain the channel 600 open.The flaps 606 are set to open during positive pressure exerted by bloodflow in the direction from the left ventricle 20 to the coronary artery26. Negative pressure or blood flow in the reverse direction at leastpartially closes the flaps 606 to minimize the flow of blood to the leftventricle 20.

[0158] The body 608 includes a periphery 610 having a thread 612integrally formed along the periphery. The thread 612 includes astarting edge 614 for engaging the face 602 and slightly dilating thediameter of the myocardium 16. As the periphery 610 is rotated, thestarting edge 614 assists the advance of the thread 612 into contactwith the face 602 of the myocardium. The thread 612 can slightly embeditself or slightly penetrate into the face 602 of the myocardium toretain the valve 604 in the self-maintained channel 600.

[0159] Another example of a mechanical means for regulating blood flowis to use a material in place of the flaps 606 which is semi-permeableto blood flow. The semi-permeable material can allow the blood to flowfrom the left ventricle while minimizing the reverse flow of blood.

[0160] The present invention also provides self-maintained channelswhich regulate the flow of blood without a synthetic valve asillustrated by the examples in FIGS. 41 and 42. Self-maintained channel620 extends completely through the myocardium 16 from the left ventricle20 to the coronary artery 26. The channel 620 includes two segments 622and 624 which are orientated at an obtuse angle to the interior side 24and exterior side 18 of the myocardium, respectively. A third segment626 connects to the other segments 622, 624 and is orientated in agenerally parallel direction relative to the sides 24, 18 of themyocardium and-a perpendicular direction to the change in the thicknessof the myocardium. Because the orientation within the myocardium of thetwo segments 622, 624 and third segment 626 are different, each of thesegments is affected differently by forces applied by the surroundingmyocardium as it contracts and relaxes during the cycle of the heart.The forces from the myocardium can change both the length and diameterof the segments 622, 624, and 626. As a result, the flow of blood isminimized into the left ventricle 20 during the cycle of the heart. Itshould be noted that arrows indicate only a general movement of themyocardium 16 in changing thickness during the heart cycle. There areforces experienced during the heart cycle within the myocardium 16 whichare not strictly orientated perpendicular to the coronary artery andleft ventricle.

[0161] Another example of a self-maintained channel which regulates theflow of blood therethrough with the natural rhythmic cycle of the heartis illustrated in FIG. 42. The self-maintained channel 640 includes abowed or curved configuration which extends completely through themyocardium 16 from the left ventricle 20 to the coronary artery 26. Withproper orientation of the bowed configuration between the interior side24 and exterior side 18 of the myocardium, the forces applied by thesurrounding myocardium as it contracts and relaxes during the cycle ofthe heart can be advantageously used to regulate the flow of bloodthrough the channel 640. The forces from the myocardium can change boththe length and diameter of the channel 640. As a result, the flow ofblood is minimized into the left ventricle 20 during the cycle of theheart.

EXAMPLES

[0162] Two sets of experiments utilizing animals were designed toevaluate the acute functionality of the inventive methods. Eachexperiment was performed on a beating heart. No type of temporary assistor heart-lung bypass technique was utilized. Anesthesia was maintainedwith oxygen administration in accordance with conventional protocol. ECGwas monitored and an arterial monitoring catheter was placed in the leftinternal mammary artery for assessment of blood pressure.

[0163] The first set of experiments was carried out on seven femaleYorkshire pigs weighing 30-35 kg. On four of the pigs, a formalsternotomy was used and in the other three pigs, a left anterior 4^(th)intercostal space thoracotomy was used. A prototype conduit wasintroduced into the left ventricle through a formal sternotomy with theother end of the conduit introduced into the left anterior descendingcoronary artery through cannualation. The left anterior descendingcoronary artery was then tied proximally. In this set of experiments,blood flow was delivered to the proximally occluded left anteriordescending artery from the left ventricular chamber through a valvedconduit, there being no other blood supply to the left anteriordescending coronary artery.

[0164] Several different types of inventive valves were incorporatedwithin the conduit. These valves consisted of a fine penrose tube or anIMA vein suspended between two ports in a chamber which could bepressurized. The IMA vein would be harvested shortly before and haveabout a 2 cm length with one or two valves. When connected in thisfashion, blood passed in a continuous path from the left ventricularchamber via the penrose tube or vein into the left anterior descendingcoronary artery. The surrounding chamber could then be pressurized toany pre-determined level and in this way, the penrose tube or vein wouldcollapse and prevent backflow when left ventricular pressure fell belowthe pressurized chamber level. The penrose tube or vein functioned in amanner commonly referred to as a “Starling resister” similar to thatillustrated in FIG. 20.

[0165] Another valve type employed a small penrose tube or a veinsegment Which was suspended from only one port in a non-pressurizedchamber with a second opening in the chamber allowing continuity ofblood flow from the left ventricle to the left anterior descendingartery. Each harvested vein graft was inserted between the twocatheters, creating a valved conduit approximately 15 mm long with anoverall length of about 10 cm for complete external pathway. In thisembodiment, any attempt at backflow of blood to the left ventricularchamber would cause collapse of the penrose tube or vein segment andocclude the backflow port.

[0166] In the seven pigs, Doppler flow measurement revealed bothsystolic and some diastolic flow in the left anterior descendingcoronary artery. Blood flow was confirmed by miniature Doppler on thedistal coronary and vein graft and the flow pattern was about systolic(80%), diastolic (20%). There was no obvious demarcation of an ischemiczone distal to the left anterior descending coronary artery ligation norwere arrhythmias or an observable decrease in left ventricularcontraction noted. The inventive conduit was left in place from 30 min.to 1 and ½ hours.

[0167] With occlusion of the conduit carrying blood from the leftventricular chamber, all of the hearts fibrillated within 3-5 minutes.This result indicated that the ventricular supply of coronary blood wasessential and provided for normal function for the duration of theexperiment.

[0168] The second set of experiments were designed to evaluate the netcoronary flow per minute whether delivered in systole or diastole, undercontrol conditions and compared these to the net coronary flow in mL/mindelivered from the left ventricle as the only source (all proximalcoronary arteries having been ligated.) In this set of experiments sixYorkshire pigs weighing 30-35 kg underwent surgical stemotomy andcannulation of the coronary sinus—the common outflow of all coronaryblood flow. The left hemiazygous vein was ligated so that coronary sinusblood was not contaminated by the systemic circulation. Under controlconditions all blood flow emanating from the coronary sinus wascollected for a specific period of time and the mL of coronary bloodflow per minute calculated. A left ventricular conduit was thensurgically inserted into the left ventricular chamber from theepicardial surface and then connected to cannulas which had beeninserted into the left and right coronary os. When the left maincoronary artery and the right coronary artery were snared around theintroduced cannula the left ventricle was the only source for coronaryblood flow. In this experimental set-up, coronary blood flow thereforeoriginated from the left ventricle and passed through a prototypeconduit and valving system as described above into the right coronary osand left coronary os. Measurement of total coronary blood flow emanatingfrom the coronary sinus under this condition demonstrated no differencein net coronary blood flow per minute from the control condition. Withthe coronary artery ligated, net coronary blood flow per minuteoriginating from the left ventricular chamber via the inventive conduitwas also measured without a valve in place. These sets of experimentsdemonstrated that net coronary blood flow per minute was similar whetherdelivered via the aortic root under control conditions or from a leftventricular source via the inventive conduit.

[0169] Several clinical discoveries were made which further support thephysiologic viability of the inventive methods. There is a similarity ofphysiology to patients with Aortic Valve Insufficiency. The deliveryrequirements per beat are very small. Continuous flow is observed duringcoronary angiograms. The mean pressure within the myocardium isrelatively low compared to systolic perfusion pressure. The animalsexperienced no change in EKG and no change in heart wall motion. Therewas no change in flow characteristics of blood. The coronary arterialsystem was compliant and enabled diastolic perfusion.

[0170] Some conclusions may be drawn from other observations. Thedynamic motion of heart muscle and subsequent motion of the conduit mayreduce stasis which contributes to clot formation. The high velocity ofdelivery from the left ventricle to the coronary artery may reduceincidence of clot formation and resulting thrombosis (occlusion). Theshort length of the conduit (approximately 15 mm) may reduce the chanceof clot formation and thrombosis (occlusion).

[0171] In comparing the inventive left ventricle to coronary arteryapproach to the conventional coronary perfusion approach, it was foundthat the same amount of blood was being delivered across the myocardiumto the coronary sinus in both approaches. Compared to conventionaltransmyocardial revasculation techniques the present invention used muchlarger holes, enabled patency of the channel and demonstrated theheart's ability to tolerate this type of intervention with littleeffect.

[0172] The present invention provides significant advantages whencompared to the prior art relating to interventional procedures such asthe ability to improve long term patency rates and reduce the high rateof retreatment. Furthermore, the present invention allows multiplevessels to be treated. Compared to CABG surgery, the present inventionis a less-invasive procedure which can be performed on a beating heartusing smaller incisions for entry than normally required by conventionaltechniques. Also, harvesting an autologous graft may not be needed.

[0173] The present invention fulfills many needs found wanting in theprior art. Many patients were not candidates for percutaneous or CABGsurgery because they could not be fully revascularized by the surgery.The present invention significantly enlarges the population of potentialcandidates. Furthermore, the use of small ports between the ribs toprovide the revascularization provides an access site in the immediatevicinity of the selected site in the arterial vascular system and avoidsthe use of a sternotomy and/or a thoracotomy. The present inventionprovides access to the arterial vascular system on both sides of theheart such as the left anterior descending artery, circumflex artery,and as well as their tributaries.

[0174] As described, the present invention fulfills many clinical needsthat are currently unmet by the prior art. For example, many patientswith coronary artery disease are not amenable to CABG or percutaneoustreatment due to their extensive disease. However, this invention offersa comparable treatment alternative to conventional techniques allowingthese patients to receive care. Furthermore, the inventive approachprovides for methods and devices that allow for coronaryrevascularization procedures to be performed through small holes insteadof a chest incision. The present invention provides access to thearterial vascular system allowing for all vessels of the heart to berevascularized.

[0175] The present invention also provides for partial revascularizationor increased flow by having a self-maintained channel or conduit withouta valve. In this embodiment, a channel is created and maintained betweenan oxygenated blood source and a site selected in the arterial vascularsystem. The channel does not incorporate means for regulating the bloodflow therethrough. More particularly, when the selected site is distalto a substantial or complete blockage or occlusion, a self-maintainedchannel or conduit without a valve between the left ventricle andselected site provides significant, but not complete, revascularizationof the selected site and the surrounding area.

What is claimed is:
 1. A method for increasing the flow of blood to aselected site in a patient's arterial vascular system of the heart, themethod comprising the steps of: creating a channel for blood flow froman oxygenated blood source to the selected site in the arterial vascularsystem of the heart; maintaining the channel in an open position forblood flow through diastolic and systolic cycles of the heart; andregulating the blood flow in the channel to minimize blood flow from thecoronary vascular system to the blood source during diastole.
 2. Themethod of claim 1 wherein the creating step includes perforating anddilating the tissue surrounding the blood source to create the channeltherein.
 3. The method of claim 1 wherein the creating step includesremoving tissue to form an aperture completely through the tissuesurrounding the blood source to partially create the channel therein. 4.The method of claim 1 wherein the creating step includes exposing atleast a portion of the patient's heart for surgical access.
 5. Themethod of claim 1 wherein the creating step includes advancing adelivery device to the tissue surrounding the blood source.
 6. Themethod of claim 1 wherein the blood source is the left ventricle and thetissue surrounding the blood source is the myocardium.
 7. The method ofclaim 1 wherein the method includes more than one blood source.
 8. Themethod of claim 1 wherein the method includes more than one site in thearterial vascular system.
 9. The method of claim 1 wherein the methodincludes selecting a site in the arterial vascular system distal to anobstruction therein.
 10. A method for performing a transmyocardialcoronary revascularization procedure for the treatment of coronaryatherosclerosis caused by an obstruction in the arterial vascularsystem, the method comprising the steps of: creating a channel for bloodflow from an oxygenated blood source to the arterial vascular systemdistal to the area of obstruction; maintaining the channel in an openposition for blood flow through the diastole and systole cycles of theheart; and regulating the blood flow in the channel to minimize bloodflow from the arterial vascular system to the blood source during thediastolic cycle of the heart.
 11. The method of claim 10 wherein thecreating step includes perforating and dilating the tissue surroundingthe blood source to create the channel therein.
 12. The method of claim10 wherein the creating step includes removing tissue to form anaperture completely through the tissue surrounding the blood source topartially create the channel therein.
 13. The method of claim 10 whereinthe creating step includes exposing at least a portion of the patient'sheart for surgical access.
 14. The method of claim 10 wherein thecreating step includes advancing a delivery device to the tissuesurrounding the blood source.
 15. The method of claim 10 wherein theblood source is the left ventricle and the tissue surrounding the bloodsource is the myocardium.
 16. The method of claim 10 wherein the methodincludes more than one blood source.
 17. The method of claim 10 whereinthe method includes more than one site in the arterial vascular system.18. The method of claim 10 wherein the method includes selecting a sitein the arterial vascular system distal to an obstruction therein.
 19. Amethod for treating an obstruction in a patient's cardiovascular systemusing a non-expandable conduit made of biocompatible material, themethod comprising the steps of: inserting the conduit completely throughthe myocardium of the patient's heart with one end of the conduitextending into the left ventricle and the other end of the conduitextending into the arterial vascular system distal to the area ofobstruction; maintaining the conduit in an open position for blood flowthrough the diastolic and systolic cycles of the heart; regulating theblood flow in the channel to minimize blood flow from the arterialvascular system to the left ventricle during the diastolic cycle of theheart.
 20. The method of claim 19 wherein the inserting step includesperforating and dilating the tissue surrounding the blood source tocreate the channel therein.
 21. The method of claim 19 wherein theinserting step includes removing tissue to form an aperture completelythrough the tissue surrounding the blood source to partially create thechannel therein.
 22. The method of claim 19 wherein the inserting stepincludes exposing at least a portion of the patient's heart for surgicalaccess.
 23. The method of claim 19 wherein the inserting step includesadvancing a delivery device to the tissue surrounding the blood source.24. The method of claim 19 wherein the blood source is the leftventricle and the tissue surrounding the blood source is the myocardium.25. The method of claim 19 wherein the method includes more than oneblood source.
 26. The method of claim 19 wherein the method includesmore than one site in the arterial vascular system.
 27. The method ofclaim 19 wherein the method includes selecting a site in the arterialvascular system distal to an obstruction therein.
 28. A method forincreasing the flow of blood to a selected site in a patient's arterialvascular system, the method comprising the steps of: inserting one endof a conduit into the left ventricle; inserting the second end of theconduit into the arterial vascular system at the selected site;maintaining the conduit in an open position for blood flow through thediastolic and systolic cycles of the heart; regulating the blood flow inthe conduit to minimize blood flow from the arterial vascular system tothe left ventricle during the systolic cycle of the heart.
 29. Themethod of claim 28 wherein the method includes connecting the ends ofthe conduit together.
 30. The method of claim 28 wherein the methodincludes: accessing the patient's myocardium; and perforating themyocardium.
 31. The method of claim 28 wherein the inserting stepincludes perforating and dilating the tissue surrounding the bloodsource to create the channel therein.
 32. The method of claim 28 whereinthe inserting step includes removing tissue to form an aperturecompletely through the tissue surrounding the blood source to partiallycreate the channel therein.
 33. The method of claim 28 wherein theinserting step includes exposing at least a portion of the patient'sheart for surgical access.
 34. The method of claim 28 wherein theinserting step includes advancing a delivery device to the tissuesurrounding the blood source.
 35. The method of claim 28 wherein theblood source is the left ventricle and the tissue surrounding the bloodsource is the myocardium.
 36. The method of claim 28 wherein the methodincludes more than one blood source.
 37. The method of claim 28 whereinthe method includes more than one site in the arterial vascular system.38. The method of claim 28 wherein the method includes selecting a sitein the arterial vascular system distal to an obstruction therein.